Fresh water supplies are becoming increasingly scarce as the world's population continues to increase. Many countries with arid climates and sporadic rainfall experience continual crop failures resulting in chronic food shortages. Most municipalities in developed countries also restrict water usage for lawns as their fresh water supply diminishes.
Systems and materials now have been developed to improve moisture retention and stabilization in soil by adding organic conditioners to help perpetuate plant growth with lower water usage. Such conditioners/stabilizers have been used in many forms, mostly using some type of cellulosic material such as dried plants from the Plantago family. The application of such conditioners/stabilizers to soil, however, generally requires extensive soil preparation, including tilling the soil, adding the stabilizer, and then tilling the stabilizer into the soil. Being organic, the level of effectiveness of the conditioners/stabilizers further has a diminishing timeline as the elements of nature break down the molecular structures of the cellulosic fibers. An example of this approach is disclosed in Doane, U.S. Pat. No. 7,009,020, which teaches methods of producing starch-graft copolymer granules to mix with fertilizer. Doane further describes the coating of seeds and plant roots with such absorbent granules. Tsujimoto, U.S. Pat. No. 5,930,949, describes methods of hydrating seeds with SAP's prior to germination, however, the SAP particles generally are separated from the seeds before they are planted.
Alternatively, surface water retention nets as described in Matsumoto U.S. Pat. No. 5,601,907 disclose the use of coating applied to a net with a water absorbing resin for the purpose of retaining moisture on the surface of the net. This netting material appears to work well for the purpose of seeding hillsides or rocky areas where vegetation is needed and the soil cannot be properly prepared before planting. However the capability of the net to absorb and retain large amounts of moisture is limited and exposure to the heat of the sun allows a large percentage of moisture to evaporate without aiding in the growth of the vegetation.
Another material, described in Hubbs U.S. Pat. No. 5,746,546, details the use of water absorbent, swellable adhesive particles mixed with textile fibers and aggregate particles. The adhesive particles bind the fibers with the aggregate, providing a surface that has a quick recovery after wet conditions. This method is advantageous in golf course sand traps or athletic fields where it is desirable to have a resilient surface without using large rock or gravel base materials. However, it does not describe a method of retaining moisture to perpetuate vegetation and decrease water usage.
Still further, Kido, U.S. Pat. No. 6,248,444, and Dohrn, U.S. Pat. No. 7,052,775, both describe methods of producing cellulosic fibers, while Saotome U.S. Pat. No. 5,026,596, describes a method of heat-bonding a SAP material to a textile substrate, for forming disposable diapers.
U.S. Pat. No. 6,178,691 teaches the production of a capillary carpet irrigation system. This product, marketed as “Aquamat™,” consists of four layers: a water impermeable base membrane of polyethylene, a water permeable microperforated dark colored top membrane, and two polyester needle punched mats of differing densities. This structure, however, requires a herbicide based root-blocking mechanism to be placed between the plants and the mat, and is not intended for permanent, subterranean installation.
Cargill, U.S. Pat. Publication No. 2005/0118383, discloses a structure having encapsulated SAP granules between multiple layers of textile fabrics. The structure retains large amounts of water and is said to offer benefits due to evaporative cooling. In addition to personal cooling devices, use of the fabric material for fire deterrent blankets also is disclosed.
It therefore can be seen that an economical subterranean geo-textile fabric capable of retaining large amounts of water and releasing it as the soil begins to dry, therefore aiding in the growth of vegetation and decreasing the amount of water required would be desirable. Such a fabric also needs to be durable, environmentally friendly, and have porosity that will not deter plant root growth or the normal transmission of moisture.